Sledge with supportive seating

The Oxford panel write:

Does anyone have any experience with/ideas for a sledge for a child (age3+) who needs supportive seating.  Mum contacted us saying that she was stuck indoors in the snowy weather because she could not use a pushchair and the lad is too heavy to carry far.  She would like something to get him to the shops and out and about….and for a bit of fun if possible.  There seem to be sledges made with seats for babies, but not for children, so before embarking on inventing something from scratch, I want to find out if there is a solution out there somewhere.

Please contact Virginia Tite virginiatite@hotmail.com if you can think of a solution to this seasonal request.